The present invention relates generally to AC-to-DC power conversion techniques, and more specifically to a technique for providing a regulated, isolated DC output voltage from a power factor corrected AC input voltage with increased efficiency.
AC-to-DC power converters are known that employ power factor correction techniques to assure low input harmonic current content. For example, a conventional two-stage AC-to-DC power converter comprises a first voltage regulator stage connected in series to a second voltage regulator stage. The first voltage regulator stage includes a power factor corrected front end operative to receive an AC power input, and to convert an AC voltage to a high level regulated DC voltage. The second voltage regulator stage comprises a DC-to-DC power supply section operative to receive the high level regulated DC voltage generated by the first voltage regulator stage, to convert the high level DC voltage to a lower level regulated DC voltage, and to provide the lower level DC voltage as an isolated DC voltage output. To regulate the DC voltages generated by the first and second stages, each stage includes a feedback control loop operative to transfer amplitude (error) information from the voltage output to the respective stage for use in adjusting the regulated DC voltages to the desired amplitude. The conventional two-stage AC-to-DC power converter described above has drawbacks, however, in that the multiple control loops associated with the first and second stages significantly increase the complexity of the power converter, thereby increasing both the size and cost of manufacture of the overall circuit.
It would therefore be desirable to have an AC-to-DC power converter that is capable of generating a regulated, isolated DC voltage output using a simpler control loop configuration. Such an AC-to-DC power converter would have a reduced size and reduced power requirements. It would also be desirable to have an AC-to-DC power converter with improved efficiency.